interpolate()

Fill in missing values by linear interpolation

Since 1.1.1

Fill in missing values by linear interpolation. Use in the same query as time_bucket_gapfill. interpolate cannot be nested inside another function call.

Arguments

The syntax is:

SELECT interpolate(
    value = <anyelement>,
    prev = <anyelement>,
    next = <anyelement>
);

Name	Type	Default	Required	Description
value	SMALLINT | INTEGER | BIGINT | REAL | DOUBLE PRECISION	-	✔	The value to interpolate
prev	EXPRESSION	-	-	If no previous value is available for gapfilling, use the prev lookup expression to get a previous value. For example, you can use prev to fill in the first bucket in a queried time range. The expression must return a (time, value) tuple with types corresponding to the bucketed times and values.
next	EXPRESSION	-	-	If no next value is available for gapfilling, use the next lookup expression to get a next value. For example, you can use next to fill in the last bucket in a queried time range. The expression must return a (time, value) tuple with types corresponding to the bucketed times and values.

Returns

Column	Type	Description
interpolate	SMALLINT, INTEGER, BIGINT, REAL, or DOUBLE PRECISION	The gapfilled value. The return type matches the input value type.